Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758847AbYAIBUf (ORCPT ); Tue, 8 Jan 2008 20:20:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757828AbYAIBUK (ORCPT ); Tue, 8 Jan 2008 20:20:10 -0500 Received: from rv-out-0910.google.com ([209.85.198.189]:45596 "EHLO rv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758045AbYAIBUI (ORCPT ); Tue, 8 Jan 2008 20:20:08 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=RFz3lUoQKGVTmQnJTP182SZ60fWtH5T9DyKZrCeObfYIQJRhhZVU/F+A0qpoWeK3w2RvrR/c59/7l9cSKwhr3ZCVzhmN0PLxYGqQLME+uXDo8clSskJkFbJB25Q4cTenERwUolY8Zg61IH01AtFkSxbsx0yd6mlbqRgNmOwDVD0= Message-ID: <412e6f7f0801081720i61bf2986md68d19db11685218@mail.gmail.com> Date: Wed, 9 Jan 2008 09:20:08 +0800 From: "Changli Gao" To: "Andi Kleen" Subject: Re: [PATCH] Improve scalability of epoll_ctl Cc: linux-kernel@vger.kernel.org In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <478397F7.1030005@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1008 Lines: 31 On Jan 9, 2008 12:56 AM, Andi Kleen wrote: > > Are you sure it's faster? vmalloc/vfree can be quite slow because > they have to change the MMU state of the kernel and take global > locks. I don't think so. In fact, the memory of fdtable is allocated by vmalloc when its size is bigger than PAGE_SIZE: static inline void * alloc_fdmem(unsigned int size) { if (size <= PAGE_SIZE) return kmalloc(size, GFP_KERNEL); else return vmalloc(size); } > > The other problem is that on 32bit systems vmalloc space is somewhat > limited -- you might have added an unintended scaling limit. As I have talked above, I am sure open(), socket() and etc. will first encounter it. -- Regards， Changli Gao(xiaosuo@gmail.com) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/